Technical Field
The present disclosure pertains to the field of lighting devices and, more specifically, proposes an add-on Indoor Positioning System (IPS) controller for a light-emitting diode (LED) lighting device.
Description of Related Art
The Global Positioning System (GPS) while effective for outdoor positioning applications has two key disadvantages when it comes to indoor use. Firstly, GPS signal is usually blocked or significantly weakened inside a building. Secondly, it doesn't differentiate on height, so it can't tell whether a person is on the first floor or the second floor inside a building. The Indoor Positioning System (IPS) recently appeared on the market overcomes these drawbacks, and furthermore provides a finer position resolution down to 10 cm, vs. 1 m by GPS. Some IPS system resides in LED lighting fixtures, and other doesn't. LED-based IPS is more popular due to the facts that lighting fixture is generally available everywhere inside a building and that a new technology, Visible Lighting Communication (VLC), enables IPS data broadcasting via LED light according to the fixture's physical location.
VLC, a subset of optical wireless communication technologies, is a data communication using visible light between 400 and 800 THz (780-375 nm). The technology transmits data by adjusting the intensity or the on-off cycle of the visible light. Popular Light Intensity Baseband Modulation (LIBM) includes On-Off Keying (OOK), Pulse Amplitude Modulation (PAM), and Pulse Position Modulation (PPM). The first general of VLC device achieved 10 kbit/s data transmission rate by using fluorescent lamp. Recently LED light source was used and this dramatically improved the VLC data rate up to 500 Mbit/s. VLC has several advantages over traditional wireless communication technologies. First of all, its spectrum is license-free. Secondly, it is free of RF health concerns. Thirdly, it has the potential of delivering ubiquitous computing since light-producing devices as such lamps (indoor/outdoor), TVs, traffic signs, street light, car headlights/taillights, and commercial displays are everywhere. VLC data communication is more secure since data can only be received where the VLC light source is visible. It is also less susceptible to RF-noise. Lastly, the high data rate offered by LED light source makes it very cost-effective for delivering large of amount of data over a short distance.
FIG. 1 depicts schematically a typical LED-based IPS system. The IPS Service Center comprises of IPS server, IPS database, and non-IPS database. The non-IPS database may contain application data such as merchandize promotion information, and the IPS database may record the indoor location of each fixture and the location association information of the merchandizes and the fixtures. The IPS server may combine the information from both database to alert the shopper inside a supermarket regarding the location and the promotion of a merchandize. The IPS server may further connect to a user profiling system over the Internet cloud service such that it can match shopper's personal purchasing preference and/or history when sending the promotional message via the IPS system.
The broadcast IPS data may be sent from the IPS server to the IPS-enabled LED lighting device via wired or wireless connection. The IPS-enabled LED lighting device may comprise of a VLC module, an LED Driver, one or more LEDs, and a two-way wireless module. After receiving the broadcast IPS data, the IPS-enabled LED lighting device may relay the information through either the VLC module or the two-way wireless module to the IPS receiver device. When relaying IPS data through the VLC module, the LIBM modulated signal stream is fed to the LED driver which in turn drives the LED diode to emit VLC encoded data by adjusting the light intensity at a frequency higher than human eye can perceive. Inside the IPS receiver device, there is a photo diode for receiving the VLC data, and the received data is fed to the VLC (software) module for demodulation. The IPS receiver device is typically a smartphone or a specially designed electronic device.
When relaying IPS data through the two-way wireless module, the data is communicated directly to the IPS receiver device wirelessly, through WiFi, Bluetooth, Low Energy Bluetooth, infrared, or any other two-way wireless communication technologies. The IPS receiver device may communicate with the two-way wireless module residing in the IPS-enabled LED lighting device, or alternatively, it may communicate through its regular wireless data communication channel directly with the IPS service center for additional information and service. The location of the IPS receiver device is calculated according to its distance relative to the closest IPS-enabled LED lighting device(s).
The conventional approach of designing an IPS-enabled LED lighting devices is to embed the VLC module and the two-way wireless module inside an integrated LED lighting device as shown in FIG. 1. This approach has the advantage of achieving the maximal controllability of the LED lighting device. It however severely limits the deployment of the IPS technology, because firstly it requires existing LED lighting devices to be replaced with IPS-enabled ones, which could induce significant costs on material and labor for replacement. Secondly, once an IPS controller is embedded inside of an LED lighting device, it can't be upgraded or improved easily. Given the long life of LED lighting device of 10-20 years, it is foreseeable that the IPS technology would make significant improvement over this time span on data transmission speed and functionality. An embedded IPS controller design would prevent the user from taking the advantage of the latest and more cost-effective IPS technology. The present disclosure overcomes the above limitations of embedded IPS controller design by extending and applying the invention of U.S. patent application Ser. No. 14/842,612, titled “Add-on VLC Controller for LED Lighting Device”, to IPS controller.